"There's a major effort underway to let a lot of people out of jail, ostensibly less violent offenders," he said. "But one of the issues of concern is when people go to jail, oftentimes they go to jail with negotiated charges, if you will, so that somebody that is in jail that seems that they're a nonviolent drug offender may in fact have crimes of violence in their record."

Howard had a long record of arrests but was sent into a diversion program despite being arrested in 2009 for a shooting, a crime he was never indicted or convicted of.

"This individual had 28 arrests — that's 28 times we got him committing a crime, let alone all the crimes that he probably committed in between us catching him," Bratton said.

Tyrone Howard had 28 arrests before he was charged with killing a New York City cop. (Jefferson Siegel/New York Daily News)

"Judges need to, and district attorneys, and we the police, the public need to take into account that some people, I'm sorry, they're criminals," he said. "This guy had been given more chances to deal with his drug addiction problem. He failed at every time, consciously failed it. Some people are bad people, and we need to separate the bad people from the good people."

He said there should be changes to the way sealed arrest records are handled, since they may prevent officials from realizing when a suspect has a history of violence.

"Oftentimes a judge, or even a district attorney, is not aware that what appears to be an extensive arrest record is even more extensive because there are a lot of sealed offenses," he said. "There's going to be a very significant reexamination of all of these issues, and I think that's needed."

Bratton has raised concerns about the federal prisoner release before, saying that the rushed effort will leave ex-cons without the services they need to avoid returning to crime, and without adequate supervision.

Under the Obama administration's initiative, prisons have been releasing inmates this weekend, beginning Friday and expected to continue until Monday.

In response to Holder's murder, Mayor de Blasio also called for changes to state bail law to allow judges to consider whether someone is a public safety risk before releasing them.